Group 2 Thermodynamics Project: We are the bestest group ever!!!!!! MD JB SK.... I would have have tried to spell something with our initials but we don't have any freakin vowels.
Compressor
Heat-exchanging pipes - serpentine or coiled set of pipes outside the unit
Expansion valve
Heat-exchanging pipes - serpentine or coiled set of pipes inside the unit
Refrigerant - liquid that evaporates inside the refrigerator to create the cold temperatures Many industrial installations use pure ammonia as the refrigerant. Pure ammonia evaporates at -27 degrees Fahrenheit (-32 degrees Celsius).
The basic mechanism of a refrigerator works like this:
The compressor compresses the refrigerant gas. This raises the refrigerant's pressure and temperature (orange), so the heat-exchanging coils outside the refrigerator allow the refrigerant to dissipate the heat of pressurization.
As it cools, the refrigerant condenses into liquid form (purple) and flows through the expansion valve.
When it flows through the expansion valve, the liquid refrigerant is allowed to move from a high-pressure zone to a low-pressure zone, so it expands and evaporates (light blue). In evaporating, it absorbs heat, making it cold.
The coils inside the refrigerator allow the refrigerant to absorb heat, making the inside of the refrigerator cold. The cycle then repeats.
Refrigeration is the process of removing heat from an enclosed space, or from a substance, to lower its temperature. A refrigerator uses the evaporation of a liquid to absorb heat. The liquid, or refrigerant, used in a refrigerator evaporates at an extremely low temperature, creating freezing temperatures inside the refrigerator. It's all based on the following physics: - a liquid is rapidly vaporized (through compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today.
Number one: Snow and ice, cool streams, springs, caves and cellars were long ago used to refrigerate food. Meat and fish were preserved in warm weather by salting or smoking.
Wooden boxes lined with tin or zinc and insulated with various materials including cork, sawdust, and seaweed were used to hold blocks of ice and "refrigerate" food. A drip pan collected the melt water - and had to be emptied daily.
Michael Farady, a Londoner who in the early 1800s liquified ammonia to cause cooling, and Dr. John Goorie of Apalachicola, Florida, who built a machine to make ice to cool the air for yellow fever patients in 1834. Today's compression refrigeration system operates on a concept adapted from Farady's experiments. It involves compressing gas into a liquid which will then absorb heat. In so doing it returns to gas. This is a simplified description of what happens in a home refrigerator, freezer, air conditioner or dehumidifier.
In 1918 Kelvinator introduced the first refrigerator with any type of automatic control. One manufacturer's 1922 model had a wooden cabinet, a water-cooled compressor, two ice cube trays and nine cubic feet of storage space. It cost $714. In 1923 Frigidaire introduced the first self-contained unit. Steel and porcelain cabinets began appearing in the mid-20s.
In the 1920s and '30s, consumers were introduced to freezers when the first electric refrigerators with ice cube compartments came on the market. Mass production of modern refrigerators didn't get started until after World War II. In the 1930s freon 12 was used to replace sulphur dioxide as the most commonly used refrigerant. During the 1940s frozen food storage became widely used by consumers Refrigeration technology began hopping in the 1950s and '60s when innovations like automatic defrost and automatic ice makers first appeared.
The environment became a top priority in the 1970s and '80s, which lead to more energy-efficient refrigerators and elimination of chlorofluorocarbons in refrigeration sealed systems
THERMOELECTRIC: Cooling is achieved electronically using the "Peltier" effect - heat is pumped with electrical energy.
COMPRESSOR : Cooling is achieved by vaporising a refrigerant (such as freon) inside the refrigerator - heat is absorbed by the refrigerant through the principle of the "latent heat of vaporisation" and released outside the refrigerator where the vapour is condensed and compressed into a liquid again. Uses mechanical energy.
ABSORPTION: Cooling is achieved by vaporising a refrigerant (ammonia gas) inside the refrigerator by "boiling" it out of a water ammonia solution with a heat source (electric or propane). Uses the principle of "latent heat of vaporisation". The vapour is condensed and re-absorbed by the ammonia solution outside the refrigerator. Uses heat energy. s.-a-refrigerator-works/
The process of refrigeration requires two important factors: the fact that a gas cools as it expands and the Second Law of Thermodynamics, which states that when two objects are near each other, the warmer one cools and the cooler one warms up.
- Compressor
- Heat-exchanging pipes - serpentine or coiled set of pipes outside the unit
- Expansion valve
- Heat-exchanging pipes - serpentine or coiled set of pipes inside the unit
- Refrigerant - liquid that evaporates inside the refrigerator to create the cold temperatures Many industrial installations use pure ammonia as the refrigerant. Pure ammonia evaporates at -27 degrees Fahrenheit (-32 degrees Celsius).
The basic mechanism of a refrigerator works like this:Refrigeration is the process of removing heat from an enclosed space, or from a substance, to lower its temperature. A refrigerator uses the evaporation of a liquid to absorb heat. The liquid, or refrigerant, used in a refrigerator evaporates at an extremely low temperature, creating freezing temperatures inside the refrigerator. It's all based on the following physics: - a liquid is rapidly vaporized (through compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today.
Number one:
Snow and ice, cool streams, springs, caves and cellars were long ago used to refrigerate food. Meat and fish were preserved in warm weather by salting or smoking.
Wooden boxes lined with tin or zinc and insulated with various materials including cork, sawdust, and seaweed were used to hold blocks of ice and "refrigerate" food. A drip pan collected the melt water - and had to be emptied daily.
Michael Farady, a Londoner who in the early 1800s liquified ammonia to cause cooling, and Dr. John Goorie of Apalachicola, Florida, who built a machine to make ice to cool the air for yellow fever patients in 1834. Today's compression refrigeration system operates on a concept adapted from Farady's experiments. It involves compressing gas into a liquid which will then absorb heat. In so doing it returns to gas. This is a simplified description of what happens in a home refrigerator, freezer, air conditioner or dehumidifier.
In 1918 Kelvinator introduced the first refrigerator with any type of automatic control. One manufacturer's 1922 model had a wooden cabinet, a water-cooled compressor, two ice cube trays and nine cubic feet of storage space. It cost $714. In 1923 Frigidaire introduced the first self-contained unit. Steel and porcelain cabinets began appearing in the mid-20s.
In the 1920s and '30s, consumers were introduced to freezers when the first electric refrigerators with ice cube compartments came on the market. Mass production of modern refrigerators didn't get started until after World War II.
In the 1930s freon 12 was used to replace sulphur dioxide as the most commonly used refrigerant.
During the 1940s frozen food storage became widely used by consumers
Refrigeration technology began hopping in the 1950s and '60s when innovations like automatic defrost and automatic ice makers first appeared.
The environment became a top priority in the 1970s and '80s, which lead to more energy-efficient refrigerators and elimination of chlorofluorocarbons in refrigeration sealed systems
http://physics.info/refrigerators/index.shtml
http://www.enotes.com/how-products-encyclopedia/refrigerator
http://www.thegeminigeek.com/how
THERMOELECTRIC: Cooling is achieved electronically using the "Peltier" effect - heat is pumped with electrical energy.
COMPRESSOR : Cooling is achieved by vaporising a refrigerant (such as freon) inside the refrigerator - heat is absorbed by the refrigerant through the principle of the "latent heat of vaporisation" and released outside the refrigerator where the vapour is condensed and compressed into a liquid again. Uses mechanical energy.
ABSORPTION: Cooling is achieved by vaporising a refrigerant (ammonia gas) inside the refrigerator by "boiling" it out of a water ammonia solution with a heat source (electric or propane). Uses the principle of "latent heat of vaporisation". The vapour is condensed and re-absorbed by the ammonia solution outside the refrigerator. Uses heat energy. s.-a-refrigerator-works/
http://www.qrg.northwestern.edu/thermo/design-library/refrig/refrig.html
The process of refrigeration requires two important factors: the fact that a gas cools as it expands and the Second Law of Thermodynamics, which states that when two objects are near each other, the warmer one cools and the cooler one warms up.